// is highp wasteful for this shader?
#ifdef GL_FRAGMENT_PRECISION_HIGH
  precision highp float;
#else
  precision mediump float;
#endif

uniform float u_time;
uniform vec2 u_resolution;

void main() {
  vec2 uv = gl_FragCoord.xy / u_resolution;

  vec3 col = 0.5 + 0.5 * cos(u_time + uv.xyx + vec3(0, 2, 4));

  gl_FragColor = vec4(col,1.0);
}